The present invention relates to a method for formulating potassium sulfate, sodium bicarbonate and sodium carbonate and more particularly, the present invention relates to a method for formulating such compounds from spent potash brine.
In a typical potash plant approximately between 85% and 90% of potassium chloride is recovered. The residual is lost due to washing with water sodium chloride from the sodium chloride during purification procedures. A second cause of the losses is occlusion of the potassium chloride in the sodium chloride tailings.
Tailing ponds are used to collect the excess brine of saturated sodium chloride and potassium chloride with the brine usually being deep well injected for disposal. As an example, for every 1,000,000 tonnes of potassium chloride produced, between 80,000 and 100,000 tonnes of potassium chloride is disposed of by deep well injection.
Generally known techniques are deficient in any clear teachings regarding the methodology set forth above having the following commercial and industrial advantages:
a) production of useful salts from material typically discarded;
b) avoidance of the requirement for deep well injection;
c) use of a nominal amount of energy to synthesize product;
d) use of common equipment widely employed in chemical engineering unit operations; and
e) environmentally friendly protocol devoid of operations which generate pollutants or otherwise adversely affect the soil or air.
There is, therefore, a clear need for a process having these desirable properties; the present invention addresses these needs in an elegant and environmentally conscious manner.
One object of the present invention is to provide an improved method for formulating useful alkali salts from waste potassium chloride.
A further object of one embodiment of the present invention is to provide a method for forming potassium sulfate from potash brines, comprising the steps of:
providing a source of sodium chloride and potassium chloride in a first step;
reacting the sodium chloride and potassium chloride with calcium sulfate and sodium sulfate;
forming a syngenite precipitate and a first filtrate;
treating the syngenite precipitate with ammonia and carbon dioxide at between 60xc2x0 C. and 100xc2x0 C.;
forming calcium carbonate precipitate and a second filtrate;
cooling the second filtrate to a temperature of between 0xc2x0 C. and 40xc2x0 C.;
treating the second filtrate with potassium chloride crystals; and
forming potassium sulfate precipitate and a third filtrate.
A further object of one embodiment of the present invention is to provide a method for forming potassium sulfate and sodium bicarbonate from potash brines, comprising the steps of:
forming potassium sulfate in a first phase and sodium bicarbonate in a second phase, the first phase, comprising the steps of:
providing a source of sodium chloride and potassium chloride in a first step;
reacting the sodium chloride and potassium chloride with calcium sulfate and sodium sulfate;
forming a syngenite precipitate and a first filtrate;
treating the syngenite precipitate with ammonia and carbon dioxide at between 50xc2x0 C. and 100xc2x0 C.;
forming calcium carbonate precipitate and a second filtrate;
cooling the second filtrate to a temperature of between 0xc2x0 C. and 40xc2x0 C.;
treating the second filtrate with potassium chloride solid;
forming potassium sulfate precipitate and a third filtrate, said second phase comprising the steps of:
treating the first filtrate with ammonia or ammonium ions and carbon dioxide; and
forming sodium bicarbonate precipitate.
Having thus described the invention, reference will now be made to the accompanying drawing illustrating preferred embodiments.